1. Field of the Invention
The present invention relates to an air conditioning system for vehicles, and, more specifically, to an air conditioning system suitable as an air conditioner for use in a work vehicle.
2. Description of the Related Art
In a vehicle having a radiator supplying water to an engine, the radiator is generally mounted in an engine compartment together with other equipments for an air conditioner. A compressor provided in a cooling circuit of the air conditioner is generally driven by using the power of an engine. If the consumptive power of the engine is too much, the engine may heat up and the water temperature in the radiator may be too hot, thereby causing the vehicle to overheat. If the vehicle overheats or a warning that the vehicle is about to overheat occurs, the operation of the vehicle is stopped or a restriction on the operation of the vehicle occurs.
In work vehicles, for example power shovels, common sized cabins are frequently used regardless of the size or weight of the vehicles. Thus, the specification and abilities of air conditioners required for such common cabins may be substantially the same. However, the engine and equipment around the engine, including the radiator, tend to become smaller as the size and weight of the vehicle decreases. Therefore, in smaller sized work vehicles:
a) The amount of power consumed to drive the compressor of the air conditioner and thus the total consumptive power of the engine is increased, and the engine tends to heat up. PA1 b) The condenser covers a greater amount of area of the radiator so that the ability of the radiator to handle heat radiation decreases. PA1 c) Because generally, the engine compartment is not too wide, the ability to exhaust heat is not good. Therefore, heat tends to be trapped in the engine compartment, and a) and b) may be exasperated.
As a result, in smaller vehicles the water temperature in the radiator tends to be high, and overheating often occurs.
Moreover, in a work vehicle, a door and/or a window may frequently be open. This causes the cooling load to increase, which causes the heat radiated from the condenser to increase, which results in a decrease in the ability of the radiator to handle the heat radiation. As a result, the water temperature in the radiator may increase and the vehicle may overheat.